1. Field of the Invention
The present invention relates to a process for preparing a layered hydrogel product, which is industrially advantageous and utilizable for confectionary industry.
2. Discussion of Background and Material Information
Conventionally, a layered hydrogel product has been prepared in the following manners:
(i) A gelling agent which is gelled by cooling, such as agar, gelatin or the like (hereinafter called as known gelling agent), is dissolved in water, then the aqueous solution is cooled to a temperature below its gelation temperature. On the gelled solution, is laminated an aqueous solution of the same or another gelling agent, such as carrageenan, pectin, gellan gum or the like, which is maintained at a temperature higher than its gelation temperature, then cooled to give a layered hydrogel product.
(ii) Specific gravities of two solutions containing gelling agents are made different by increasing or decreasing their water-soluble solid contents, then the two solutions in sol state are laminated and cooled to give a layered hydrogel product.
Neither of these processes are industrially advantageous. Namely, the method (i) requires the gelation of the first aqueous solution of a gelling agent by cooling to a temperature below its gelation temperature, to laminate the second solution on the first solution and to again cool the combined product, with the result that energy loss in the cooling steps becomes considerably high and the process becomes complicated. Further, in this method (i), the two layers tend to be detached from each other at the interface. In the method (ii), although the specific gravities of the two solutions are made different, tastes, colors, fragrances and the like contained in each of the solutions are mixed when the two solutions are poured into a mold, so that the value of the product is significantly degraded. Further, the pouring operation must be carefully and slowly conducted, resulting in a disadvantageous industrial application.